U.S. Pat. No. 5,589,555 (Zboril et al. issued Dec. 31, 1996) and U.S. Pat. No. 5,519,098 (Brown et al. issued May 21, 1996) both assigned to Novacor Chemicals (International) S.A. (now NOVA Chemicals (International) S.A.) disclose catalysts for the solution polymerization of alpha olefins. The patents disclose a catalyst system comprising:
(i) a mixture of a trialkyl aluminum compound and a dialkyl magnesium compound; PA1 (ii) a reactive chloride which may be an alkyl halide; PA1 (iii) a transition metal compound; and PA1 (iv) the reaction product of a trialkyl aluminum compound and an alcohol in amounts up to about stoichiometric amounts to produce a dialkyl aluminum alkoxide. PA1 (i) a mixture of an alkyl aluminum compound of the formula (R.sup.1).sub.3 Al and (R.sup.2).sub.2 Mg, wherein R.sup.1 is a C.sub.1-10 alkyl radical and R.sup.2 is a C.sub.1-10 alkyl radical in a molar ratio of Mg to Al from 4.0:1 to 5.5:1; PA1 (ii) a halide of the formula R.sup.3 X, wherein R.sup.3 is a C.sub.1-10 alkyl radical and x is a halide selected from the group consisting of chlorine and bromine; PA1 (iii) titanium tetrachloride; and PA1 (iv) an alkyl aluminum alkoxide compound of the formula (R.sup.4).sub.2 AlOR.sup.5, wherein R.sup.4 and R.sup.5 are independently selected from the group consisting of C.sub.1-10 alkyl radicals to provide: a molar ratio of Mg:Ti from 4:1 to 5.5:1; a molar ratio of aluminum alkyl to titanium tetrachloride from 1:1 to 1.5:1; a molar ratio of halide to Mg from 1.9:1 to 2.5:1; and a molar ratio of alkyl aluminum alkoxide to titanium from 1.2:1 to 2:1. PA1 (i) a mixture of an alkyl aluminum compound of the formula (R.sup.1).sub.3 Al and (R.sup.2).sub.2 Mg, wherein R.sup.1 is a C.sub.1-10 alkyl radical and R.sup.2 is a C.sub.1-10 alkyl radical in a molar ratio of Mg to Al from 4.0:1 to 5.5:1; PA1 (ii) a halide of the formula R.sup.3 X, wherein R.sup.3 is a C.sub.1-8 alkyl radical and x is a halide selected from the group consisting of chlorine and bromine; PA1 (iii) titanium tetrachloride; and PA1 (iv) an alkyl aluminum alkoxide compound of the formula (R.sup.4).sub.2 AlOR.sup.5, wherein R.sup.4 and R.sup.5 are independently selected from the group consisting of C.sub.1-10 alkyl radicals to provide: a molar ratio of Mg:Ti from 4:1 to 5.5:1; a molar ratio of aluminum alkyl to titanium tetrachloride from 1:1 to 1.5:1; a molar ratio of halide to Mg from 1.9:1 to 2.5:1; and a molar ratio of alkyl aluminum alkoxide to titanium from 1.2:1 to 2:1.
The present invention has removed the step in the process of the above patents of the reaction of a trialkyl aluminum compound with an alcohol. In these prior patents the molar ratio of aluminum (the first addition Al.sup.1) to transition metal is 0.9. The ratio of halide to magnesium is from 1.9:1 to 2.6:1. The ratio of aluminum (second addition-the reaction product of the trialkyl aluminum and alcohol) to transition metal is at least 3:1. The above patents do not disclose a catalyst system in which the mole ratio of the second addition of aluminum to transition metal is below 3:1, more particularly in the range from 1.2:1 to 2:1.
U.S. Pat. No. 4,097,659 issued Jun. 27, 1978 to Creemers et al. and assigned to Stamicarbon, N.V. (now expired), discloses a process for producing polyolefins in which a precursor is prepared by reacting an aluminum alkyl halide of the formula R.sub.m AlX.sub.3-m with an organomagnesium compound of the formula MgR'.sub.2 wherein m is a value less than 3. That is, the aluminum compound may have 1, 2 or 3 halogen atoms; and R and R' independently may be a C.sub.1-30 hydrocarbyl radical. The Creemers patent does not teach or suggest that the first component could be the reaction product of a trialkyl aluminum compound and a dialkyl magnesium compound. In fact, the patent teaches against such a system as illustrated by the comparative example in which the first component is prepared by reacting trimethyl aluminum and dibutyl magnesium. The resulting reaction product is then reacted with a transition metal compound. The molar ratio of magnesium and aluminum to transition metal may be from between 0.1:1 and 10:1. The resulting precursor is then activated with an organoaluminum activator selected from the group consisting of trialkyl aluminum, an alkyl aluminum halide and an alkyl aluminum hydride. Creemers does not teach nor suggest the activator could be a dialkyl aluminum alkoxide. In short, the patent teaches away from the subject matter of the present invention.
European patent application 0 280 353 in the name of Coosemans et al., assigned to Stamicarbon B.V., published 31.08.88, teaches a two component catalyst system for the solution polymerization of olefins. The first component comprises a mixture of one or more magnesium compounds, one or more aluminum compounds and one or more transition metal compounds, optionally in the presence of a halogen containing compound. The second component is an activator which is an organoaluminum compound of the formula R.sup.1.sub.m Al X.sub.3-m. In the first component the ratio of Al:Mg is greater than 1 (claim 1 and page 2 line 26). In the catalysts of the present invention the ratio of magnesium to aluminum is from 4.0:1 to 5.5:1 (therefore the ratio of aluminum to magnesium is from 0.25:1 to 0.18:1) which is well below that specified in the Coosemans patent. Additionally, in component 1 of Coosemans the ratio of Al:transition metal is at least 3:1 (claim 1) while in the present composition the ratio of aluminum to transition metal is from about 1:1 to 1.3:1. In view of the foregoing the Coosemans patent teaches away from the subject matter of the present invention.
U.S. Pat. No. 4,314,912 issued Feb. 9, 1982 to Lowery, Jr. et al., assigned to The Dow Chemical Company teaches a catalyst which is a reaction product of a transition metal, an organomagnesium compound, a non-metallic monohalide (x=halide). In the catalyst the ratio of Mg: Transition metal is from 5:1 to 2000:1; Mg:X is from 0.1:1 to 1:1 (e.g. 1:10 to 1:1) and the ratio X: transition metal is from about 40:1 to 2000:1. In the catalysts of the present invention the ratio of X to Mg is about 2:1 and the ratio of Mg: transition metal is about 5:1. Accordingly the ratio of X to transition metal is about 10:1 which is well below the amount specified in the Lowery patent.
The present invention seeks to provide a catalyst useful in high temperature solution polymerization.